I’ve always been told that after the fall of the Western Roman Empire, Rome itself had declined extensively, both in infrastructure and in population. What parts of Rome itself were lived in during the medieval and Renaissance periods? Was there more of a population concentration around St. Peter’s because of the Pope’s influence? What about the original city center? Was the ancient city itself (the open section between the Palatine and Capitoline Hills) used for anything? Like how the Arch of Constantine was part of a walled estate and used as a gate (was told this by an art history professor a while back). This in particular sparked my curiosity, because from what I understand the arch is located near the original city center and became part of an estate? I guess what I’m curious for is a picture of how Rome changed over the ages on a city layout basis, if this makes sense. Any information or sources would be great!

(Clearly not a historian, so if what I said is incorrect feel free to correct me!)